Enhance mov dr instruction emulation used by SVM so that it properlyhandles dr4/5: alias to dr6/7 if cr4.de is cleared. Otherwise returnEMULATE_FAIL which will let our only possible caller in that scenario,ud_interception, re-inject UD.

We do not need to inject faults, SVM does this for us (exceptions takeprecedence over instruction interceptions). For the same reason, thevalue overflow checks can be removed.